Pilot error has not been ruled out as a cause of the Asiana Airlines plane crash at San Francisco International Airport that killed two people and left 182 injured Saturday, CNN reports.

In a news conference held Sunday, Deborah Hersman, the chairwoman of the National Transportation Safety Board, said the plane was flying well below its target speed and was "approaching a stall" moments prior to impact. Hersman said that data from the recording device onboard the plane indicated that the crew received a call to increase speed seven seconds before the crash. The Boeing 777, which originated in Shanghai, China and stopped in Seoul, South Korea, was flying dangerously close to the water as it attempted to land, survivors told CNN. It eventually crashed into the runway, landing on its tail, resulting in a large fireball and a charred roof. CNN has video of the crash here.

When asked whether pilot error may have played a part, Hersman said "nothing has been ruled out. We will not speculate and will not draw conclusions" until more information is known about what happened. An investigation into the crash has already begun and the results may not be determined for up to two years, according to South Korea's Aviation Policy Bureau. The pilot behind the controls is a 17-year veteran of Asiana Air.

The Asiana Airlines Flight 214 crash took the lives of two female students from China who were on their way to a summer camp: Wang Linjia and Ye Mengyuan, both 16.

Two of the people who were brought to local hospitals with spinal injuries are now paralyzed and eight were still listed in critical condition as of Sunday afternoon, according to the Los Angeles Times. Several survivors had been treated and discharged. Some of the patients had burn injuries indicating that they may have been dragged along the runway as the plane came to a halt, the Times reports. An additional 123 people of the 305 passengers on board walked away without injuries.

This is the third deadly crash for Asiana Air in the past two decades, CNN reports. In 1993, a plane crashed in poor weather near South Korea's Mokpo Airport, killing 68 people. In 2011, a cargo plane carrying two people from Seoul to Shanghai crashed into the East China Sea, killing both.